Synthetic resin from phenols and acetylenic acids



invention.

PatentedJuly 21, 1942 SYNTHETIC RESIN FROM PHENOLS AND ACETYLENIC ACIDS Alexander Douglas Macallum, London, Ontario, Canada, assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Original application July 22, 1938,

Serial No. 226,793. Divided and this application February 1, 1941, Serial No. 376,992

8 Claims. (Cl. 260-47) This invention relates to synthetic resins of a new type and more particularly to the prepare--v tion of resins by reacting propiolic acid or other alpha acetyienic acid with certain organic hy-' droxy compounds. This is a division of my copending application Serial No. 220,793, filed July 22, 1938 now Patent No. 2,249,535, issued July 15, 1941.

It is an object of my invention to provide synthetic resins of a new typ which are useful as ingredients in coating compositions and in preparing molded articles of manufacture. It is a further object to provide a method of preparing these resins wherebypropiolic acid and/or a homolog thereof is reacted with certain organic hydroxy compounds. particularly certain polyhydric alcohols. These and other objects will be apparent from the ensuing description of my I have discovered that when propiolic acid is reacted with organic hydroxy compounds of the class set forth below, e. g. by heating the acid and the hydroxy compound in the presence or absence of a suitable catalyst, a complex resinous reaction product is. formed instead of a simple ester. Although the exact nature of the reaction which occurs is not entirely understood, its occurrence to form resins is apparently due to the bifunctional character of propiolic acid andto -30 the presence in the hydroxy compound of not less than two reactive constituents, at least one of which is a hydroxyl group. Evidence at hand indicates that the reactions which take place involve both the carboxyl and the acetylenic groups of the pr'opiohc acid molecule and at least two reactive constituents in the molecule cthe hydroxy compound, at least one of these constituents being an hydroxyl group.

The present resins may be formed and the above objects may be accomplished in accordthan these may be employed. Catalysts, e. g;

acids or acid salts, such as those commonly employed in esteriflcation or etheriflcation reactions, may be added to the mixture in order to accelerate the reaction or to facilitate its 55 currence at a temperature lower than would otherwise be necessary. However, the presence of such catalyst is not essential. Also in the case of the less reactive or the insoluble or diiiicultly soluble hydroxy compounds, certain salts or substances may be added to the reaction mixture, the function of these added agents being to increase the solubility of the hydroxy compound in the reaction mixture or to cause its 10 swelling, as for instance in the case of cellulose,

whereby reaction may thus be facilitated.

The following compounds are illustrative of the hydroxy compounds which may be used as reactants in the formation of the present resins:

l5 ethylene glycol, propylene glycol, butylene glycol,

trimethylene glycol, tetramethylene glycol, pentaglycol, and diethylene glycol and polyglycols generally; glycerol and polyglycerols generally; erythritol, pentaerythrite, arabitol, xylitol, mannitol, dulcitol and sorbitol; polyvinyl alcohol,

and carbohydrates generally such as sucrose, maltose, lactose, glucose, celluloses and starches; phenol, cresols, thymols and other unsubstituted or partly substituted monohydric phenols; naphthols; polyhydric phenols such as resorcinol,

quinol, catechol, pyrogailol. phloroglucinol and the like.

As regards the monohydric phenols-it should be stated that so far as I am aware only those monohydric phenols which have at least one unsubstituted orthoor para-position in the aromatic nucleus are suitable as reactants in forming the present resins. Furthermore, of all of the hydroxy compounds which may be reacted in accordance withthe present invention some are considerably more reactive than others and give products which are much more attractive from a practical standpoint. Accordingly, I prefer to practice my invention employing as a reactant, a polyhydric alcohol since polyhydric alcohols are generally more reactive and produce moreuseful resin products. In particular, I prefer to prepare the present resins employing ethylene glycol, glycerol, pentaerythrite or polyparticularly the dihydric, trihydric and tetrahydric alcohols, may be used with excellent resul s.

The exact nature of the reactions by which the present resins are formed is not well understood; however, it is known that the resulting resins consist chiefly of complex esters or mixtures thereof. Furthermore, it is believed. that the resins produced from polyhydric alcohols are complex ester acetals or esterketals. In the vinyl alcohol, although other polyhydric alcohols,

sented asfollows:

H2O =0 The products obtained are, in fact, much more complex than indicated by the above formulae, being most probably mixtures of polymers derived from the above acetal or ketal esters by formation of cross-linkages between two or more such molecules with the production of aggregates, the

solubility and plasticity of which will depend upon the molecular size and character of the aggregates as determined, for example, by the relatively straight or branched chain structure of the polymer. The polyfunctionality of the initial reactants increases the number of ways in which in molecular proportions of 0.66 mol of 91% acid they can react and thus accounts for the formation of such heat-hardened resinous polymers from propiolic acid and the hydroxy compounds set forth above.

In the case of ethylene glycol, resin formation may be visualized as resulting from acetal or ketal formation involving hydroxyl groups of the glycol and the acetylenic group of the acid, together with ester formation involving a hydroxyl group of the glycol and the carboxyl group of the acid. The reaction mechanism is probably similar to that suggested above when glycerol is employed as the hydroxy compound. Similar mechanisms may be postulated to explain the formation of the resinous products from other polyhydric alcohols and propiolic acid.

The reaction with monohydric phenols is believed to involve the addition of phenol residues to the triple bond "of propiolic acid together with the esterification of the carboxyl group of the acid. There is some evidence that in the addition at the triple bond an orthoor para-hydrogen atom 'of the phenol adds to the alpha or beta carbon atom of the acid molecule resulting in the production of complex internal ester derivatives of hydroxylated diphenyl 'propionic acids. Here, the active orthor para hydrogen atom of the phenolacts as does the hydrogen atom of the hydroxyl group in the case of polyhydric alcohols. While any monohydric phenol which is unsubstituted in at least one ortho or para position may be expected to react in accordance with the present invention, such monohydric phenols are considerably less reactive than the polyhydric phenols. Thus quinol is much more reactive than phenol.

The formation of resinous products in accordance with my invention is illustrated by the following examples: 1

I Example 1 of 110-115"- C. for about 140 hours. The weight of the resultingproduct was about 78% of the weight of the original reactants. The product,

containing about 41.7% of combined propiolic acid, comprised a pale brown, viscous, watersoluble, liquid resin serving as a good plasticizer for certain polyvinyl alcohol esters. It could be converted by continued heating at 150 C. to a transparent, brownish, solid resin which is hard, tough and insoluble in water.

Example 2 An equimolecular mixture oi 91% propiolic acid and 95% glycerol was heated at -115 C. for hours to give a yellow, water-soluble viscous liquid containing substantially no free acid and approximately 39.6% by weight of combined propiolic acid. In a similar experiment employing the same quantity of reactants, the reaction mixture was heated at a temperature of C. for 18 hours to obtain a brownish-yellow, hard, tough resin which was insoluble in water and which contained approximately 51.3% of combined acid. The liquid product obtained by heating the reaction mixture at 110-115" C. could also be converted to a hard, tough, insoluble resin similar to that obtained by heating at 150 C. by subjecting it to a further heat treatment at a temperature above the temperature originally used, e. g'. at 150 C. In one experiment a reaction mixture consisting of one mol of 95% glycerol and approximately two mols of 91% propiolic acid was heated at ll0- ll5 C. for 94 hours to obtain a brown, hard, tough, insoluble resin containing approximately'56.9% by weight of combined acid.

The experimental results which have been obtained show that not much more than about one mol of propiolic acid will react with three hydroxyl groups of glycerol, even though a large excess of the acid is employed. This can be interpreted as evidence that the reaction involved probably results mainly in the formation of polymerized internal ester acetal or ester ketal derivatives of glycerol and either formyl acetic or I pyruvic acid, respectively.

Example 3 A mixture of pentaerythrite and 1.33 molecular proportions of 91% propiolic acid was heated 48 hours at a temperature of 110-115 C. The resultingproduct comprised a soft, straw-colored, rubbery material when wet, a tough, leathery material when dry. It was insoluble in water and most organic solvents other than glycol or propiolic or propionic acids in which it dis.- solved in the cold. Baked for a time at 150, it set to a hard, tough,.yellow resin, apparently soluble only in hot propiolic acid or glycol.

Example 4 A 10% aqueous solution of high viscosity polyvinyl alcohol, 6.7 parts by weight, was treated with 1 part of 97.8% propiolic acid and the solution heated in the form of a thin film on glass at immersed in boiling water the film could be stripped off cleanlyby use of a straight edged A mixture of propiolic acid and ethylene glycol 15- tool to yield a transparent, tough, flexible but found to be more adherent and to contain the equivalent of 12.3% of combinedpropiolic acid.

Example 5 Sucrose, heated-for about 85 hours at 85C. with 2.96 molecular; proportions of 96.8%

propiolic acid and a trace ofv hydrogen chloride,

was converted to a black, stifi" tar which was sparingly soluble in water, alcohols, acetone, ethers, chloroform and acids but. readily soluble in propiolic acid and formainide. The black tar was purified by dissolving in formamide and precipitating from the resulting solution with water. Dried in vacuo at ordinary temperature,

7 the produce comprised hard, lac-like flakes, pulverizing to a brown, granular powder. The latter did not fuse at temperatures up to 240 C. 5

140-150 C., the hardened resin being insoluble in It appeared from cold saponification with -alcoholic potash to contain 31.2% of combined propiolic acid as against 31.4% calculated for a sucrose dipropiolate.

Example 6 I A mixture of 9.4 grams of phenol, 7 grams of propiolic acid with 1.8 grams of zinc bromide added as catalyst, was heated 6 days at 85 C. to produce a red, transparent, easily fusible solid which was freed from volatile'by-products and unreacted phenol by steam distillation. The distillation residue comprised a brownish, solid resin fusing at (SO-70 C. which corresponded roughly in composition to a polymerized internalester of adihydroxy diphenyl propionic acid. 40

An equimolecular mixture of quinol and propi olic acid was subjected to prolonged heating at 115 C. and the resulting product fre'd from unreacted quinol by dissolving in ethyl acetate and fractionally precipitating with petroleumether. The precipitated product was a dark colored resin of molecular. weight between 1200 and 1500 grams.

ance with the present invention is not restricted to the use of the specified hydroxy compounds alone as reactants with the propiolicacid, since other compounds commonly employed as reactants to modify properties of synthetic resins may be employed if desired. Thus, I have found that drying oils or. unsaturated,long-chain fatty acids may be added to ,the reaction mixture for the purpose of modifying theproperties of the resin. 6

In this manner resins may be obtained which are especially attractive for use as ingredients in varnishes. Thepreparation of such modified I resins is illustrated by the next example.

Example 8 g The resulting product comprised an oil and a solid, both orange-colored. The oil contained 29.7% and the solid 59.9% of combined acid, calculated as propiolic acid, The oil was miscible with hydrocarbon solvents, vegetable oils and certain alcohols such as ethanol and butanol. It

was superior to linseed oil in'both'drying and baking properties.

Homologues of propiolic acid, e. g.- methyl, ethyhpropyl and amyl propiolic acids and the like, may be used in placeof propiolic acid as the acid reactant in the preparation of the present resins. acid since it is more readilyavailable than are its higher homologues. The following example illustrates the reaction between ,tetrolic (methyl propiolic) acid and glycerol.

7 Example 9 A mixture containing 1.5. molecular proportions .of tetrolic'acid to 1 molecular proportion'of glyc- 'erol-was heated for about 300 hours at -115 C., whereupon a brown, tacky, water-soluble resin was obtained which contained approximately 63.2% of combined acid. This product hardened upon being heated for 12-18 hours in air at with the present invention by incorporating into the propiolic acid-hydroxy compound reaction mixture modifying reactants such as the polybasic acids used in the preparation of polyhydric alcohol-polybasic acid resins, or the intermediate phenol-formaldehyde condensation products such as the phenol alcohols or diphenylol methanes.

Illustrative of the polybasic acids which may.

be used for this purposeare phthalic acid, succinic acid, citric acid and the like. The proportion of modifying reactant employed may be varied widely depending upon the particular properties desired of the resin product. The modifying reactant may be added at any desired stage of the preparation. When a polybasic acid is employed, it may be preferable in some cases to effect a partial reaction between the polyhydric alcohol and the polybasic acid before adding propiolic acid. The exact procedure to be followed in any specific case will depend upon the specific reactants employed, the conditions under which reaction is to be expected and upon the properties desired in the final product.

In preparing the present resins the tempera- 55 ture at which the reaction should be effected will The formation of resinous products in accordmodification'ofjmy invention, I effect the initial reaction at a relatively low temperature, e. g. 80-120? C., and then complete the reaction, e. g. after the intermediate product hasbeen applied to surfaces as a, coating or has been molded, by subjecting it to a relatively high temperature,

.Various proportions of the hydroxy compound and propiolic acid, or a homologue thereof, may

be used in practicingv the present invention. Whether or not an excess of one or the other reactant is employed will depend upon the nature of resin desired. In general I find it economical to employ approximatelyone mol of propiolic acid for each quantity of the hydroxy compound However, I prefer to employ propiolic corresponding to three reactive constituents in the hydyroxy compound. Thus, when a polyhydric alcohol is employed a quantity of the-alcohol corresponding to three hydroxyl groups per mol of propiolic acid is employed. In the case of monohydric phenols I prefer to employ a quanthe scope of my invention. Also resins may be prepared by reacting a mixture of hydroxy compounds with propiolic acid or by reacting almixture of homologues of propiolic acid with one or more hydro'xy compounds. Whether or not mixtures of the type suggested above should be employed will depend to a large extent upon the desired properties of the resin and its intended use.

The present resins, particularly those obtained by the use of ethylene glycol, glycerol, pentaerythrite or polyvinyl alcohol, are heat-hardenable and well adapted for use in preparing coating and molding compositions. When thermally set, they are characterized by their insolubility in water and in practically all organic solvents. They may be employed in combination with other resinous substances or their properties may be varied considerably by the use in conjunction therewith of known blending or modifying agents commonly employed in resin compositions. In modifying the. properties of the resins, modifying agents may be added to the resin after its preparation or to the reaction mixture during the course of the reaction. The modifying agent employed may be one that enters into the reaction by which the resin is formed, e. g. linseed oil as in Example 8 or a polybasic acid, or it may be unreactive and act merely as a plasticizer or blending agent. Also, various fillers may be incorporated into the resins. Thus, it is evident that the properties of the resins may be varied widely depending upon the intended use thereof.

The use of substances to catalyze the reaction by which the resins are formed, although not essential, is frequently desirable, especially when ,the reaction proceeds slowly. For this purpose, hydrogen halides and other acids or acid salts such as those commonly used in catalyzing esteriflcation or etheriiication reactions may be used to advantage. Also, when the hydroxy compound is insoluble or but slightly soluble in propiolic acid. substances such as zinc bromide, zinc chloride, lithium chloride, magnesium iodide, sodium iodide or potassium thiocyanate may be added to the reaction mixture to swell or increase the solubility of the hydroxy compound, e. g. carbohydrates, in the mixture. The presence of such compounds appears, in some instances, to

' have a catalytic eifect upon the reaction in addition to its solubilizingefiect upon the hydroxy compound.

My invention is not restricted to any of the specific proportions, procedural details or ingredients set forth hereinabove, which are intended to :be merely illustrative and not restrictive, but includes all such variations, modifications and equivalents as fall within the scope pended-claims.

I claim: V 4

l. The process for producing a resin which comprises heating to reaction temperature; a monobasic acetylenic acid having the general formula RCEC-COOH wherein'R is a member of the group consisting of hydrogen and alkyl. with a phenol selected from the group consisting of monohydric phenols having an unsubstituted orthoor para-pciition and polyhydric phenols. Y

ZHIh'e process for producing a resinwhich 'comprisesheating to reaction temperature; .pro-

piolic acid with a phenol selectedfrom the group consisting of monohydric phenols having an unsubstituted orthoor para-position and polyhydric phenols.

3. The process for producing a resin which comprises heating to reaction temperature; a monobasic acetylenic acid having the general formula RCEC-COOH wherein R is a member of the group consisting 'of hydrogen and alkyl, with I phenol (CaHsOI-I).

4. The process for producing a resin which comprises heating to reaction temperature; propiolic acid with phenol (CoHsOH) 5. A'synthetic, heat hardening resin obtained by heating to reaction temperature; a monobasic acetylenic acid having the general formula RCECCOOH wherein R is a member of the group consisting of hydrogen and alkyl, with a phenol selected from the group consistingof monohydric phenols having an unsubstituted orthoor para-position and polyhydric phenols.

6. A synthetic, heat hardenable resin obtained by heating to reaction temperature; propiolic acid with a phenol selected from the group consisting of monohydric phenols having an un-- substituted orthoor para-position and poly- .hydric phenols.

7. A synthetic, heat hardenabieresin obtained by heating to reaction temperature; a monobasic acetylenic acid having the general formula RCEC-COOH wherein R. is a member of the group consisting of hydrogen and alkyl, with ALEXANDER DOUGLAS MACALLUM.

of the ap- CERTIFICATE OF CORRECTION. V Patent -No. 90,619. July 1, 1914 ALEXANDER DOUGLAS MACALLUM.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correetionas follows: Page 1.1., sec- 0nd column, iine 59, claim 5, for Khardening read --hardenable--; and that the said Letters Patent .should be read with this correction therein that the same may conionn to the record of the case in the Patent Office.

Signed ani sealed this 1st day of Septeniber, A. D. 1914. 7

Henry Van Arsdele (Seal) Acting Commissioner of Patents. 

